Civil Engineering Reference
In-Depth Information
Figure 3.41 shows an example of large-scale lateral spreading caused by liquefaction
during the Loma Prieta earthquake on October 17, 1989. As shown in Fig. 3.41, as the dis-
placed ground breaks up internally, it causes fissures, scarps, and depressions to form at
ground surface. Notice in Fig. 3.41 that the main ground surface cracks tend to develop par-
allel to each other. Some of the cracks have filled with water from the adjacent waterway.
As the ground moves laterally, the blocks of soil between the main cracks tend to settle and
break up into even smaller pieces.
Large-scale lateral spreads can damage all types of structures built on top of the lateral
spreading soil. Lateral spreads can pull apart foundations of buildings built in the failure
area, they can sever sewer pipelines and other utilities in the failure mass, and they can
cause compression or buckling of structures, such as bridges, founded at the toe of the fail-
ure mass. Figure 3.42 shows lateral spreading caused by liquefaction during the Prince
William Sound earthquake in Alaska on March 27, 1964, that has damaged a paved park-
ing area.
Lateral spreading is discussed further in Sec. 9.5.
3.5 SLOPE MOVEMENT
3.5.1
Types of Earthquake-Induced Slope Movement
Another secondary effect of earthquakes is slope movement. As indicated in Tables 3.1 and
3.2, there can be many different types of earthquake-induced slope movement. For rock
slopes (Table 3.1), the earthquake-induced slope movement is often divided into falls and
slides. Falls are distinguished by the relatively free-falling nature of the rock or rocks,
FIGURE 3.41
Lateral spreading caused by the Loma Prieta, California, earthquake on October 17, 1989.
(
Photograph from the Loma Prieta Collection, EERC, University of California, Berkeley.
)
